(a) Field of the Invention
The present invention relates to a rain sensor having a frost sensing function, more particularly, to a rain sensor that is attached to a windshield glass of a vehicle to detect raindrops and frost on the surface of the glass and output signals to control a wiper and an air conditioning system of the vehicle depending on types and amounts of substances detected and a drop cycle of raindrops.
(b) Description of the Related Art
In certain rain-sensing wiper systems, when a rain sensor provided in a vehicle detects raindrops and foreign matter on a windshield glass of a vehicle, a control signal is output to operate a wiper of the vehicle so that raindrops and foreign matter on the windshield glass of the vehicle are removed.
However, in cold weather conditions, frost is frequently formed on the interior side surface of the windshield glass of the vehicle due to a temperature difference between the interior and exterior of the vehicle, which may obstruct the driver's view. However, current systems lack a function to remove the frost in a convenient way.
That is, although the driver can remove the frost through an air conditioning system such as a heater and/or a heating wire, there is inconvenience in that the driver manually operates the air conditioning system every time because typically once the frost starts to be generated, the frost continues to be generated even after being removed.
Therefore, it is desirable to provide a rain sensor having a frost sensing function that can assist in driving the vehicle in such a manner that the frost sensing function is added to the rain sensor to detect rainfall and/or generation of frost so as to automatically operate the air conditioning system.
On the other hand, regarding the technology for removing the frost generated on the glass of the vehicle, Korean Laid-Open Patent Publication No. 10-2011-0068307 (“the '307 Publication”) discloses an apparatus and method for removing frost from the window of a vehicle, and Korean Patent Publication No. 10-0229772 (“the '772 Publication”) discloses a device for generating a voice alarm upon detecting ice on a windshield glass.
In the '307 Publication, if an outdoor air temperature detected by an outdoor air sensor and the type of current-set heating modes fulfill a predetermined determination condition, a value of flow voltage corresponding to the current outdoor air temperature is transmitted automatically to a drive unit of a blower, and ultimately the frost can be removed through flow rate and discharge intensity of air discharged from a heater.
In the '772 Publication, when an engine of a vehicle does not start, values detected by a windshield glass weight sensor and an outdoor air temperature sensor are analyzed, and if it is determined that ice exists on the windshield glass, an air conditioning system is activated and then a voice message of the current situation is output. That is, if the weight of the windshield glass is increased and the outdoor air temperature corresponds to an ice formation temperature, the air conditioning system is activated such that the ice on the windshield glass can be removed.
The above-described publications each disclose removing frost by use of an outdoor air temperature sensor, which has the possibility of malfunctioning due to an error of temperature prediction and non-uniformity of temperature distribution.
Therefore, it is desirable to develop a technology that can directly detect frost such that both rainfall and/or generation of frost can be detected, rather than by utilizing a method for predicting generation of frost through an outdoor air temperature and sensing the frost.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.